Through the eyes of a sea lion
Sarah Miller
Richard Dubielzig, DVM, DACVP
Large Diameterflattened cornea
Shorter internal axial lengthmore accurately defines optical function
The GlobeCornea thicker peripherally
Due to stroma
The CorneaFlattened region over a stenopaic pupil
not seen histologically
The cornea
Bowman’s membraneTEM
Descemet’s thin
Endothelium thin
Anterior Uvea
Extensive constriction of pupil protects from large changes in illumination
Iridocorneal angle
Thick pectinate ligament with intermittent open channels
Intermittent corneoscleraltrabecular meshwork
Anterior Uvea
Dilator muscle
absent at the pupil
Robust near iris base where it abutts sphincter m.
Near pectinate ligament
Extends over widened base of ciliary processes
Sphincter muscleThickest near iris base
Near pectinate ligament
Accomodation??
Ciliary Body
Dilator muscle extending up the base of the ciliary processes
Circumferential smooth muscle subtending zonular ligaments
accomodation??
Lens attachment: direct attachment of ciliary processes
zonular fibers
http://lifestyle.iloveindia.com/lounge/images/facts-about-pinniped-2.jpg
The Lens
Spherical lens
Spherical lensHeterogeneous (multifocal) Lower R.I. in peripheryCompensates for the inability of the cornea to refract
underwater
Tapetum lucidum
• Tapetum lucidum covers 2/3 to entire fundus
Extremely thick both dorsal & ventral to optic nerve
Tapetum lucidum
Ganglion cells!!
Dog
Pinniped
Monochromatic
loss of S opsin
Ganglion cells!!Very large but sparce
Sclera• Thick
– Near limbus– Near optic nerve
• Thin– At equator
Similar to the vascular plexus seen in cetaceans?
Vascular Plexus
Similar to the vascular plexus seen in cetaceans?
Vascular Plexus
References
•• Miller S., Miller S., ColtizColtiz C., C., DubielzigDubielzig R. (2010) R. (2010) Anatomy of the California sea lion Anatomy of the California sea lion globeglobe. Veterinary Ophthalmology supplement 1: 63. Veterinary Ophthalmology supplement 1: 63‐‐71.71.
•• YaYa SupinSupin, Alexander, et al. , Alexander, et al. The Sensory Physiology of Aquatic Mammals.The Sensory Physiology of Aquatic Mammals.Boston, Boston, KluwerKluwer Academic Publishers, 2001. (pp 239Academic Publishers, 2001. (pp 239‐‐264)264)
•• Mass A. & Mass A. & YaYa SupinSupin A. (2007) A. (2007) Adaptive Features of Aquatic MammalsAdaptive Features of Aquatic Mammals’’Eye.Eye. The Anatomical Record 290:701The Anatomical Record 290:701‐‐715.715.
•• PeichlPeichl L. et al. (2001) L. et al. (2001) For Whales and Seals the Ocean is Not Blue: A For Whales and Seals the Ocean is Not Blue: A Visual Pigment Loss in Marine Mammals. Visual Pigment Loss in Marine Mammals. European Journal of European Journal of Neuroscience 13: 1520Neuroscience 13: 1520‐‐1528.1528.